I've found that you only need to copy that folder, remove the newer version, and install the older.
User profile location in Chrome (stable, beta, dev)
XP: C:\Documents and Settings\<Username>\Local Settings\Application Data\Google\Chrome\User Data
Vista/Win7: C:\Users\<Username>\AppData\Local\Google\Chrome\User Data
User profile location in Chrome (canary)
XP: C:\Documents and Settings\<Username>\Local Settings\Application Data\Google\Chrome SxS\User Data
Vista/Win7: C:\Users\<Username>\AppData\Local\Google\Chrome SxS\User Data
Unfortunately, it may cause some issues, because Chrome shows the following alert on every start:
Your profile can not be used because it is from a newer version of
Google Chrome.
Some features may be unavailable. Please specify a different profile
directory or use a newer version of Chrome.